U.S. patent application number 12/233318 was filed with the patent office on 2010-03-18 for jumpless phase modulation in a polar modulation environment.
This patent application is currently assigned to Infineon Technologies AG. Invention is credited to Michael Wilhelm.
Application Number | 20100067617 12/233318 |
Document ID | / |
Family ID | 41795216 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100067617 |
Kind Code |
A1 |
Wilhelm; Michael |
March 18, 2010 |
Jumpless Phase Modulation In A Polar Modulation Environment
Abstract
The present disclosure relates to circuits and methods for
improving the performance of a polar modulator by maintaining the
input to a phase modulator.
Inventors: |
Wilhelm; Michael;
(Furstenfeldbruck, DE) |
Correspondence
Address: |
LEE & HAYES, PLLC
601 W RIVERSIDE AVENUE, SUITE 1400
SPOKANE
WA
99201
US
|
Assignee: |
Infineon Technologies AG
Neubiberg
DE
|
Family ID: |
41795216 |
Appl. No.: |
12/233318 |
Filed: |
September 18, 2008 |
Current U.S.
Class: |
375/308 |
Current CPC
Class: |
H03C 5/00 20130101; H04L
27/2003 20130101 |
Class at
Publication: |
375/308 |
International
Class: |
H04L 27/20 20060101
H04L027/20 |
Claims
1. A circuit, comprising: a phase shifter configured to selectively
shift a phase of a baseband phase signal one hundred eighty degrees
in accordance with a zero crossing signal to output a selectively
phase-shifted signal; a phase modulator configured to provide a
phase modulated carrier signal in accordance with the selectively
phase-shifted signal; and an inverter configured to selectively
invert the phase modulated earner signal in accordance with the
zero crossing signal.
2. The circuit according to claim 1, wherein a phase of the
selectively phase-shifted signal is continuous when the circuit
detects zero crossing or near zero crossing in a constellation
diagram.
3. The circuit according to claim 1, wherein the zero crossing
signal corresponds to a zero crossing event within a predetermined
polar modulation scheme.
4. The circuit according to claim 1, wherein the baseband phase
signal corresponds to a digital information stream.
5. The circuit according to claim 1 further comprising: an
amplitude modulator configured to provide an amplitude modulated
signal in accordance with a baseband amplitude signal; and a mixer
configured to modulate an amplitude characteristic of the
selectively inverted phase modulated signal in accordance with the
amplitude modulated signal so as to derive a polar modulated
carrier signal.
6. The circuit according to claim 5, wherein the baseband amplitude
signal corresponds to a digital information stream.
7. A modulation circuit, comprising: a phase shifter configured to
selectively shift a phase of a baseband phase signal one hundred
eighty degrees in accordance with a zero crossing signal to output
a selectively phase-shifted signal; a phase-lock loop configured to
provide a phase modulation signal in accordance with the
selectively phase-shifted signal; a variable controlled oscillator
configured to provide a differential phase modulated signal in
accordance with the phase modulation signal, the differential phase
modulated signal provided by way of a first node and a second node;
and a switch configured to selectively route the differential phase
modulated signal from the first node and the second node to a third
node and a fourth node in accordance with the zero crossing
signal.
8. The modulation circuit according to claim 7, wherein the switch
is further defined by a crossover switch configured to: couple the
first node to the third node and couple the second node to the
fourth node in response to a first state of the zero crossing input
signal; and couple the first node to the fourth node and couple the
second node to the third node in response to a second state of the
zero crossing input signal.
9. The modulation circuit according to claim 8 further comprising:
an amplitude modulator configured to provide an amplitude
modulation signal in accordance with an amplitude input signal; and
a mixer coupled to the third node and the fourth node, the mixer
configured to mix the differential phase modulated signal and the
amplitude modulation signal so as to derive a polar modulated
earner signal.
10. The modulation circuit according to claim 9, wherein: the
baseband phase signal and the amplitude input signal respectively
correspond to a digital baseband signal; and the zero crossing
signal corresponds to a zero crossing event within a predetermined
polar modulation scheme.
11. The modulation circuit according to claim 7, wherein the
modulation circuit is configured to operate in accordance with a
digital symbol constellation of at least four symbols.
12. The modulation circuit according to claim 7, wherein a phase of
the selectively phase-shifted signal is continuous when the circuit
detects zero crossing or near zero crossing in a constellation
diagram.
13. The modulation circuit according to claim 7, wherein the
modulation circuit is at least partially defined by an integrated
circuit.
14. A method, comprising: selectively shifting a phase of a
baseband phase signal one hundred eighty degrees in accordance with
a zero crossing signal to output a selectively phase-shifted
signal; deriving a phase modulated radio frequency carrier signal
from the selectively phase-shifted signal; and selectively
inverting the phase modulated radio frequency carrier signal in
accordance with the zero crossing signal.
15. The method according to claim 14, wherein: the phase modulated
radio frequency carrier signal is further defined by a differential
phase modulated radio frequency carrier signal provided at a first
electrical node and a second electrical node; the selectively
inverting the phase modulated radio frequency carrier signal
includes selectively coupling the first electrical node to either a
third electrical node or a fourth electrical node according to the
zero crossing signal; and the selectively inverting the phase
modulated radio frequency carrier signal also includes selectively
coupling the second electrical node to either the fourth electrical
node or the third electrical node according to the zero crossing
signal.
16. The method according to claim 14 further comprising: deriving
an amplitude modulated signal from an amplitude input signal; and
mixing the selectively inverted phase modulation signal and the
amplitude modulated signal so as to derive a polar modulated radio
frequency carrier signal.
17. An apparatus, comprising: a source of electrical energy; and an
electronic circuit coupled to the source of electrical energy, the
electronic circuit configured to: selectively shift a phase of a
baseband phase signal one hundred eighty degrees in accordance with
a zero crossing signal to output a selectively phase-shifted
signal; derive a phase modulated carrier signal from the
selectively phase-shifted signal; selectively invert the phase
modulated signal in accordance with the zero crossing signal;
derive an amplitude modulated signal from a baseband amplitude
signal; and mix the selectively inverted phase modulated carrier
signal with the amplitude modulated signal so as to derive a polar
modulated carrier signal.
18. The apparatus according to claim 17, wherein the apparatus is
configured to perform one or more wireless functions using the
polar modulated carrier signal.
19. The apparatus according to claim 17, wherein the baseband
phase-shifted signal and the baseband amplitude signal respectively
correspond to a digital information stream.
20. The apparatus according to claim 17, wherein the zero crossing
signal corresponds to zero crossing event within a predetermined
polar modulation scheme, the polar modulation scheme defined by a
constellation of at least four digital symbols.
Description
BACKGROUND
[0001] Digital communications use a variety of earner signal
modulation schemes. Numerous of these utilize in-phase (I) and
quadrature (Q) signals to modulate baseband information onto a
radio frequency (RF) carrier. The respective I and Q signals are
phase-orthogonal to one another and are readily represented in a
Cartesian coordinate system. However, noise filtering and other
performance considerations have motivated the development of other
modulation schemes known as polar modulation. Therein, time-varying
amplitude (A) and phase angle (.PHI.) signals are used to modulate
baseband information onto a RF carrier. Polar modulation generally
achieves better signal quality and less electrical current
consumption compared to IQ modulation techniques.
[0002] FIG. 1 graphically depicts an illustrative polar modulation
scheme in accordance with known techniques for a four-symbol
digital communication environment. Digital baseband
information--that is, the digital intelligence to be modulated onto
a carrier wave--is represented by a time-varying amplitude signal
100 and a time-varying phase signal 102.
[0003] FIG. 2 is a block diagram depicting an illustrative polar
modulation system 200 in accordance with known techniques. The
system 200 includes a phase modulator 202 configured to modulate
the phase of a radio frequency (RF) earner signal in accordance
with a baseband phase signal input. The system 200 also includes a
mixer 204 that receives the phase modulated RF carrier signal from
the phase modulator 202. The system 200 further includes an
amplitude modulator 206 configured to provide an amplitude
modulation signal to the mixer 204 in accordance with a baseband
amplitude signal input. The mixer 204 modulates the amplitude of
the phase modulated RF carrier signal in accordance with the
amplitude modulation signal from the amplitude modulator 206. The
mixer 204 thus provides a polar modulated earner signal.
[0004] Returning to FIG. 1, the illustrative polar modulated
carrier signal is graphically depicted in a constellation diagram
104. The constellation diagram 104 includes four, two-bit digital
symbols 106, 108, 110 and 112, respectively. In this way, the
constellation diagram 104 can be referred to as a constellation of
four symbols 106-112, each represented by a particular polar
modulation of the RF carrier signal. Under the present
illustration, a stream of digital baseband information is modulated
onto an RF earner signal one symbol--two digital bits--at a time.
It is important to note that a polar modulation system (e.g.,
system 200) must be able to accommodate "zero crossings" of the
digital baseband information during such an operation.
[0005] By way of example, and not limitation, the constellation
diagram 104 depicts an operational instance wherein the digital
information "1100" is modulated onto the RF carrier signal. Thus,
the symbol 106 and then the symbol 110 must be sequentially
modulated onto the RF carrier. In doing so, the baseband amplitude
signal 100 swings from full value, to zero, and then back to full
value in the time domain, an operation readily accommodated by the
amplitude modulator (e.g., 206). However, the baseband phase signal
102 is required to instantaneously shift one-hundred eighty degrees
in the time domain--a situation referred to herein as a "zero
crossing" scenario. As a result, a compliant phase modulator (e.g.,
202) must accommodate nearly infinite frequencies--something
impossible to realize thus far without distortions due to the
limited bandwidth inherent to known real-world implementations.
While the illustrative polar modulation scenario described above is
set in the context of four digital symbols, it is to be appreciated
that other polar modulation schemes (and their corresponding
constellations) having other symbol counts (e.g., eight, sixteen,
etc.) are contemplated herein.
[0006] FIG. 3 graphically depicts phase modulator 202 output signal
characteristics during zero crossing by way of respective signal
plots 302 and 304. In any case, polar modulation methods and
systems that address the foregoing considerations are
desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The detailed description is described with reference to the
accompanying figures. In the figures, the left-most digit(s) of a
reference number identifies the figure in which the reference
number first appears. The use of the same reference numbers in
different instances in the description and the figures may indicate
similar or identical items.
[0008] FIG. 1 is a diagram depicting polar modulation signals in
accordance known techniques.
[0009] FIG. 2 is a block diagram depicting a polar modulation
system according to known techniques.
[0010] FIG. 3 includes two signal diagrams according to known
techniques.
[0011] FIG. 4 is a polar modulation system according to the present
teachings.
[0012] FIG. 5 includes two signal timing diagrams according to the
present teachings.
[0013] FIG. 6 is a flow diagram depicting operational steps in
accordance with the present teachings.
[0014] FIG. 7 is another polar modulation system in accordance with
the present teachings.
[0015] FIG. 8 is a block diagram depicting an apparatus in
accordance with the present teachings.
DETAILED DESCRIPTION
[0016] Disclosed herein are improved techniques for improving the
performance of a polar modulator. Techniques in accordance with the
present disclosure may advantageously improve operating bandwidth
when transmitting digital information by way of a polar modulated
earner signal. In general, such techniques are useful in a wide
range of applications, including wireless Internet access, audio
and/or video communications, and so on.
[0017] According to one implementation, a circuit is disclosed. The
circuit may comprise at least a phase shifter, a phase modulator,
and an inverter. The phase shifter selectively shifts a phase of a
baseband phase signal one hundred eighty degrees in accordance with
a zero crossing signal to output a selectively phase-shifted
signal. The phase modulator provides a phase modulated earner
signal in accordance with the selectively phase-shifted signal. The
inverter selectively inverts the phase modulated carrier signal in
accordance with the zero crossing signal.
[0018] According to another implementation, a modulation circuit is
disclosed. The modulation circuit may comprise a phase shifter, a
phase-lock loop, a variable controlled oscillator, and a switch.
The phase shifter is configured to selectively shift a phase of a
baseband phase signal one hundred eighty degrees in accordance with
a zero crossing signal to output a selectively phase-shifted
signal. The phase-lock loop is configured to provide a phase
modulation signal in accordance with the selectively phase-shifted
signal. The variable controlled oscillator is configured to provide
a differential phase modulated signal in accordance with the phase
modulation signal, the differential phase modulated signal provided
by way of a first node and a second node. The switch is configured
to selectively route the differential phase modulated signal from
the first node and the second node to a third node and a fourth
node in accordance with a zero crossing input signal.
[0019] According to still another implementation, a method is
performed at least in part by an electronic circuit. The method
includes selectively shifting a phase of a baseband phase signal
one hundred eighty degrees in accordance with a zero crossing
signal to output a selectively phase-shifted signal. The method
also includes deriving a phase modulated radio frequency carrier
signal from the selectively phase-shifted signal. The method
further includes selectively inverting the phase modulated radio
frequency earner signal in accordance with the zero crossing
signal.
[0020] In yet another implementation, an apparatus includes a
source of electrical energy. The electronic circuit also includes
an electronic circuit coupled to the source of electrical energy.
The electronic circuit is configured to selectively shift a phase
of a baseband phase signal one hundred eighty degrees in accordance
with a zero crossing signal, derive a phase modulated radio
frequency carrier signal, and selectively invert the phase
modulated radio frequency carrier signal in accordance with the
zero crossing signal. The electronic circuit is further configured
to derive an amplitude modulated signal from a baseband amplitude
signal and mix the selectively inverted phase modulated earner
signal with the amplitude modulated signal so as to derive a polar
modulated earner signal.
[0021] Circuits and other functional aspects provided herein can be
fabricated, at least in part, on a common substrate such that one
or more respective integrated circuit devices are defined. In one
or more implementations, at least a portion of the functional
subject matter presented herein can be fabricated within a 130, 90,
65, 45, or 32 nanometer (or smaller) environment.
[0022] The techniques described herein may be implemented in a
number of ways. Illustrative context is provided below with
reference to the included figures and ongoing discussion.
[0023] First Illustrative Implementation
[0024] FIG. 4 is a block diagram depicting a polar modulation
system 400 in accordance with the present teachings. The system 400
includes a phase shifter 401 and a phase modulator 402. The phase
shifter 401 is configured to selectively shift the phase of a
baseband phase signal .PHI.(t) one hundred eighty degrees in
accordance with the instantaneous state of a zero crossing input
signal to output a selectively phase-shifted signal. The phase of
the baseband phase signal is selectively shifted one hundred eighty
degrees to output a selectively phase-shifted signal when zero
crossing occurs. The baseband phase of the baseband phase signal is
not shifted when no zero crossing occurs. The signal .PHI.(t) is
time-variant and corresponds to a predefined digital symbol
modulation scheme (constellation). The phase modulator 402 is
configured to modulate the phase of an RF earner signal in
accordance with the selectively phase-shifted signal.
[0025] The system 400 also includes an amplitude inverter 404. The
amplitude inverter 404 is configured to selectively invert (i.e.,
swap polarities, or "flip") the amplitude characteristic of the
phase modulated RF carrier signal in accordance with the
instantaneous state of a zero crossing input signal. The overall
operation of the system is as follows. When zero crossing occurs,
the baseband phase signal .PHI.(t) undergoes a phase shift of one
hundred eighty degrees, phase modulation, and amplitude inversion.
When zero crossing does not occur, the baseband phase signal
.PHI.(t) undergoes only phase modulation without undergoing a phase
shift of one hundred eighty degrees or amplitude inversion. The
state of the zero crossing signal can be determined according to
the next required polar modulation dictated by the digital baseband
information stream. By example, and not by limitation, a look-up
table or state machine (not shown) designed in accordance with the
corresponding symbol constellation can be used to provide the zero
crossing signal. The zero crossing signal is time-synchronized with
the baseband phase signal .PHI.(t). In one or more implementations,
the zero crossing signal is provided as a single-bit digital
signal, such as "0" representing no zero crossing and "1"
representing zero crossing or near zero crossing (see discussion
below), or vice versa. In any case, the zero crossing signal is
readily derived, the phase of the baseband phase signal is
selectively shifted one hundred eighty degrees, and the amplitude
inverter 404 selectively inverts the phase-modulated RF carrier
signal accordingly.
[0026] Another similar scenario, "near zero crossing" is also
considered. A "near zero crossing" occurs when the signal
trajectory approaches the origin of the constellation diagram at a
predetermined distance. A circuit can be designed to detect the
distance of the signal trajectory to the origin of the
constellation diagram. When the distance is below the predetermined
distance, the value of the zero crossing signal changes from "0" to
"1" or vice versa. Also, the zero crossing signal can be designed
in another way. For example, the zero crossing signal can be a
continuous signal, defining the distance of the signal trajectory
to the origin of the constellation diagram, instead of a single-bit
digital signal. In this situation, a "near zero crossing" occurs
when the zero crossing signal is smaller than a predetermined value
or/and a phase jump bigger than a predetermined value.
[0027] The system 400 also includes an amplitude modulator 406. The
amplitude modulator 406 is configured to receive a baseband
amplitude signal A(t) and to provide a corresponding amplitude
modulation signal. The baseband amplitude signal A(t) is
time-variant and corresponds to the same predefined digital symbol
constellation as that of the baseband phase signal .PHI.(t). The
system further includes a mixer 408. The mixer 408 is configured to
receive the selectively inverted phase-modulated RF carrier signal
from the amplitude inverter 404 and the amplitude modulation signal
from the amplitude modulator 406. In turn, the mixer 408 modulates
the amplitude characteristic of the selectively inverted
phase-modulated RF carrier signal, thus deriving a polar modulated
earner signal. The polar modulated carrier signal can then be
further processed and/or utilized (e.g., power amplified,
transmitted as a wireless signal, etc.).
[0028] When zero crossing occurs, the baseband phase signal
.PHI.(t) has a phase change of one hundred eighty degrees. However,
the phase shifter 401 also shifts back one hundred eighty degrees.
Therefore, the phase input to the phase modulator 402 is
continuous, without any abrupt changes. Also, even when a near zero
crossing occurs, the phase input to the phase modulator 402 is
still almost continuous with only a very small variation. Thus, the
modulation quality is still improved. The result is a modulation
system 400 in which the phase modulator 402 can function without
the distortion that typically occurs during normal zero crossing
operation. Also, the bandwidth requirements of the phase modulator
are relaxed and modulation quality is improved. Greater overall
polar modulated carrier signal fidelity and data bandwidth (i.e.,
throughput) are achieved by way of the system 400,
[0029] FIG. 5 graphically depicts phase modulator 402 output signal
characteristics during zero crossing by way of respective signal
plots 502 and 504.
[0030] Illustrative Method
[0031] FIG. 6 is a flow diagram depicting a method 600 according to
the present teachings. The method 600 includes particular steps and
order of execution. However, it is to be understood that other
methods respectively including other steps, and/or omitting one or
more of the depicted steps, and/or proceeding in other orders of
execution may also be used in accordance with the present
teachings. Therefore, the method 600 is illustrative and
non-limiting with respect to the operations contemplated by the
present teachings.
[0032] At 602, the phase of a baseband phase signal is selectively
shifted one hundred eighty degrees in accordance with a zero
crossing signal to output a selectively phase-shifted signal when
zero crossing occurs. The phase of the baseband phase signal is not
shifted when no zero crossing occurs.
[0033] At 604, a phase modulated carrier signal is derived in
correspondence to the selectively phase-shifted signal after the
selectively phase-shifted signal undergoes phase modulation.
[0034] At 606, the amplitude characteristic of the phase modulated
carrier signal derived at 604 above is selectively inverted in
accordance with the zero crossing signal. As used herein, inversion
refers to flipping the polarity (or sign) of the carrier signal
with respect to its original polarity. However, the instantaneous
time-rate-of-change of the phase modulated carrier signal, in the
absolute sense, is not affected. The inverted signal is essentially
a mirror image of the original phase modulated signal. In any case,
either the original (non-inverted) or the inverted phase modulated
earner signal is routed on for further processing in accordance
with the method 600.
[0035] At 608, an amplitude modulation signal is derived in
accordance with a baseband amplitude signal. The amplitude
modulation signal corresponds to the same digital symbol
constellation as that used at 604 above.
[0036] At 610, the amplitude characteristic of the (original or
inverted) phase modulated carrier signal is modulated in accordance
with the amplitude modulation signal derived at 608 above. In so
doing, a polar modulated earner signal is derived. The polar
modulated carrier signal corresponds to a predetermined digital
symbol constellation (e.g., four symbols, eight symbols, etc.). As
such, the polar modulated carrier signal conveys a stream of
digital information in accordance with a predetermined
communications protocol.
[0037] At 612, the polar modulated carrier signal is used to
perform a wireless function used for all digital modulation
standards, such as Universal Mobile Telecommunications System
(UMTS) and Long Term Evolution (LTE). By way of example, and not by
limitation, the polar modulated earner signal is used to facilitate
an Internet browsing session by way of a cellular telephone and a
cellular services infrastructure (i.e., service provider). Any
number of other illustrative and non-limiting usage scenarios can
also be performed using the polar modulated carrier signal
generating in accordance with the method 600.
[0038] Second Illustrative Implementation
[0039] FIG. 7 is a block diagram depicting another implementation
of polar modulation system 700 in accordance with the present
teachings. The system 700 includes a phase shifter 701 and a phase
lock loop (PLL) 702. The phase shifter 701 is configured to
selectively to shift the phase of a baseband phase signal .PHI.(t)
one hundred eighty degrees to output a selectively phase-shifted
signal in accordance with the instantaneous state of a zero
crossing input signal. When zero crossing occurs, the baseband
phase signal .PHI.(t) undergoes a phase shift of one hundred eighty
degrees. When no zero crossing occurs, the phase of the baseband
phase signal .PHI.(t) is not shifted. The PLL 702 is configured to
receive selectively phase-shifted signal. The PLL 702 is further
configured to generate and provide a phase modulation signal to a
variable controlled oscillator (VCO) 704 of the system 700.
[0040] The system 700 also includes the VCO 704 as introduced
above. The VCO 704 is configured to provide a phase modulated
carrier (output) signal in response to the phase modulation signal
from the PLL 702. In turn, the phase modulated carrier signal from
the VCO 704 is coupled back to the PLL 702 and is used to regulate
the phase modulation signal generated thereby. In this way, a
feedback control relationship is established and the PLL 702 and
the VCO 704 cooperatively define a phase modulator.
[0041] It is important to note that the VCO 704 provides the phase
modulated carrier signal as a differential or "floating" output
signal by way of respective nodes 706 and 708. In one
implementation, the VCO 704 is configured such that node 706 is
always of positive electrical polarity relative to node 708. Other
implementations employing other polarity configurations of nodes
706 and 708 can also be used. In any case, the phase modulated
carrier signal provided by the VCO 704 can be coupled to (or
accessed) in an inverted or non-inverted manner.
[0042] The system 700 includes a crossover switch (switch) 710. The
switch 710 is configured to selectively couple the phase modulated
carrier signal as provided at nodes 706 and 708 to a pair of switch
710 output nodes 712 and 714, respectively, in accordance with the
instantaneous state of a zero crossing signal (ZCS). In one
implementation, the zero crossing signal is a single-bit digital
signal. In one illustrative and non-limiting implementation, the
switch 710 is configured to operate according to TABLE 1 below:
TABLE-US-00001 TABLE 1 ZCS Node 706 Coupling Node 708 Coupling
Output State 0 Node 712 Node 714 Non-Inverted 1 Node 714 Node 712
Inverted
[0043] Thus, in accordance with TABLE 1 above, the switch 710
couples (i.e., connects) node 706 directly to node 712, and couples
node 708 directly to node 714, in response to a "0" (i.e.,
non-inverted) state of the zero crossing signal. Conversely, the
switch 710 couples node 706 directly to node 714, and couples node
708 directly to node 712, in response to a "1" (i.e., inverted)
state of the zero crossing signal. Other implementations of the
crossover switch 710 can also be used. In any case, the switch 710
is configured to selectively invert the phase modulated carrier
signal presented at output nodes 712 and 714 under the control of
the zero crossing signal.
[0044] The system 700 also includes an amplitude modulator 716. The
amplitude modulator 716 is configured to receive a baseband
amplitude signal A(t) and provide (i.e., output) a corresponding
amplitude modulation signal. The system 700 further includes a
mixer 718. The mixer 718 is configured to receive the selectively
inverted phase modulated carrier signal at nodes 712 and 714 and
the amplitude modulation signal from the amplitude modulator 716
and provide (i.e., output) a polar modulated carrier signal. The
polar modulated carrier signal corresponds to a predetermined
digital symbol constellation (e.g., four symbols, eight symbols,
sixteen symbols, etc.).
[0045] The system 700 is illustrative of a polar modulation system
(or circuitry) in accordance with the present teachings. In this
system, the phase input to the phase modulator 402 is continuous,
without any abrupt changes. As a result, overall signal distortion
is reduced and data throughput is increased under system 700
relative to that of known polar modulation techniques (e.g., system
200).
[0046] Illustrative Apparatus
[0047] FIG. 8 is a block diagrammatic view depicting a wireless
device (i.e., apparatus) 800 including aspects of the present
teachings. For purposes of non-limiting example, the wireless
device 800 is presumed to include various resources that are not
specifically depicted in the interest of clarity. The wireless
device 800 is further presumed to be configured to perform in one
or more wireless operating modes (e.g., cellular communications,
global positioning system (GPS), UMTS and LTE receptions,
etc.).
[0048] The wireless device 800 includes a circuit 802. The circuit
802 includes, among other possible features, a polar modulator 804.
The polar modulator 804 is configured to perform in accordance with
the present teachings. Thus, the polar modulator 804 can be
implemented by way of the polar modulation system 400 or the polar
modulation system 700. Other implementations in accordance with the
present teachings can also be used. In any case, the polar
modulator 804 provides a polar modulated radio frequency (RF)
earner signal configured to convey digital information in
accordance with a predetermined digital symbol constellation.
[0049] The wireless device 800 further includes a source of
electrical energy or "power source" 806. In one or more
implementations, the power source 806 is defined by one or more
batteries. In other implementations, the power source 806 may be
defined by an inductively coupled power supply that is energized by
an electromagnetic illumination field provided by some entity
external to the wireless device 800. Other types of power source
806 may also be used. In any case, the power source 806 is coupled
so as to provide electrical energy to the circuit 802. In this way,
the wireless device 800 is presumed to be operable in a portable
manner.
[0050] The wireless device 800 further includes an antenna 808. The
wireless device 800 is presumed to operate by way of wireless
signals 810, including the polar modulated carrier signal discussed
immediately above, between the antenna 808 and a wireless network
812. A single cellular tower 812 is depicted in the interest of
simplicity. However, it is to be understood that other resources
(not shown) of a corresponding wireless network are also present
and operative as needed so as to enable the wireless device 800 to
perform its various functions (cellular communications, Internet
access, etc.). The wireless device 800 is a general and
non-limiting example of countless devices and systems that may be
configured and operating in accordance with the means and
techniques of the present teachings.
CONCLUSION
[0051] For the purposes of this disclosure and the claims that
follow, the terms "coupled" and "connected" have been used to
describe how various elements interface. Such described interfacing
of various elements may be either direct or indirect. Although the
subject matter has been described in language specific to
structural features and/or methodological acts, it is to be
understood that the subject matter defined in the appended claims
is not necessarily limited to the specific features or acts
described. Rather, the specific features and acts are disclosed as
preferred forms of implementing the claims.
* * * * *